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My husband is concerned about how long the wood used to make the boxes lasts. Can anyone tell me how often you have to rebuild your boxes due to rotten wood. We have built boxes with 2 x 6' and 5/8" plywood bottoms in order to elevate them so my husband can garden from his wheelchair.

The best choices in wood are redwood, cedar and cypress because they resist bugs and rot and last the longest. They are much more expensive than fir or pine though. I have had good results with "painting" my raised beds with a coat or two of food grade flaxseed oil. "Boiled linseed oil" used by furniture makers to preserve or finish furniture is actually flaxseed oil with chemical thinners added to make furniture dry faster. It is poisonous and should not be used for food applications. However, you can get pure flaxseed oil at health food stores and some grocery stores. It takes a very long time to fully dry but that isn't a problem. Just brush it on the inside (and outside if you want to but I don't) and wait a day or so before installing your weed barrier. Don't forget to drill your 1/4" holes for each square foot of your raised bed first. I also use 3/4" exterior plywood instead of 5/8" and stainless steel screws with washers to attach the bottom to the 2" x 6" frame. I hope these will last at least 5-6 years. If your raised bed will be longer than 4', I would also install a cross brace two by four across the middle of the length of the bed to prevent bowing which could potentially cause an unsafe condition for your husband. Hope this helps. Happy Gardening!

I used raw linseed oil on the inside and outside of my boxes because the only wood available was pine. I have no idea how long it will last. The raw linseed oil I found at an old time hardware store. The owner said, in the old days, all the southern country boys used to put lumber down on the bottom of their pickup trucks and used raw linseed oil to preserve the wood. Also, a friend of a friend said his father (a full blooded indian?) also used the linseed oil.